Dataset Information

Decreased mitochondrial D-loop region methylation mediates an increase in mitochondrial DNA copy number in CADASIL.

ABSTRACT:

Background

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a typical neurodegenerative disease associated with mitochondrial dysfunction. Methylation of the D-loop region and mitochondrial DNA copy number (mtDNAcn) play a critical role in the maintenance of mitochondrial function. However, the association between D-loop region methylation, mtDNAcn and CADASIL remains unclear.

Methods

Overall, 162 individuals were recruited, including 66 CADASIL patients and 96 age- and sex-matched controls. After extracting genomic DNA from the peripheral white blood cells, levels of D-loop methylation and mtDNAcn were assessed using MethylTarget sequencing and real-time PCR, respectively.

Results

We observed increased mtDNAcn and decreased D-loop methylation levels in CADASIL patients compared to the control group, regardless of gender stratification. Besides, we found a negative correlation between D-loop methylation levels and mtDNAcn. Mediation effect analysis shows that the proportion of the association between mtDNAcn and CADASIL that is mediated by D-loop methylation is 11.6% (95% CI 5.6, 22.6). After gender stratification, the proportions of such associations that are mediated by D-loop methylation in males and females were 7.2% (95% CI 2.4, 19.8) and 22.0% (95% CI 7.4, 50.1), respectively.

Conclusion

Decreased methylation of the D-loop region mediates increased mtDNAcn in CADASIL, which may be caused by a compensatory mechanism of mitochondrial dysfunction in patients with CADASIL.

SUBMITTER: Zhang J

PROVIDER: S-EPMC8725280 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:The profound impact of mitochondrion in cellular metabolism has been well documented. Since type 2 diabetes (T2D) is a metabolic disorder, mitochondrial dysfunction is intricately linked with the disease pathogenesis. Mitochondrial DNA (mtDNA) variants are involved with functional dysfunction of mitochondrion and play a pivotal role in the susceptibility to T2D. In this study, we opted to find the association of mtDNA variants within the D-loop hypervariable region I (HVI), haplogroups and mtDNA copy number with T2D in Bangladeshi population. A total of 300 unrelated Bangladeshi individuals (150 healthy and 150 patients with T2D) were recruited in the present study, their HVI regions were amplified and sequenced using Sanger chemistry. Haplogrep2 and Phylotree17 tools were employed to determine the haplogroups. MtDNA copy number was measured using primers of mitochondrial tRNALeu (UUR) gene and nuclear β2-microglobulin gene. Variants G16048A (OR:0.12, p = 0.04) and G16129A (OR: 0.42, p = 0.007) were found to confer protective role against T2D according to logistic regression analysis. However along with G16129A, two new variants C16294T and T16325C demonstrated protective role against T2D when age and gender were adjusted. Haplogroups A and H showed significant association with the risk of T2D after adjustments out of total 19 major haplogroups identified. The mtDNA copy numbers were stratified into 4 groups according to the quartiles (groups with lower, medium, upper and higher mtDNA copy numbers were respectively designated as LCN, MCN, UCN and HCN). Patients with T2D had significantly lower mtDNA copy number compared to their healthy counterparts in HCN group. Moreover, six mtDNA variants were significantly associated with mtDNA copy number in the participants. Thus, our study confers that certain haplogroups and novel variants of mtDNA are significantly associated with T2D while decreased mtDNA copy number (though not significant) has been observed in patients with T2D. However, largescale studies are warranted to establish association of novel variants and haplogroup with type 2 diabetes.

Project description:IntroductionAicardi-Goutières Syndrome (AGS) is a rare encephalopathy with early onset that can be transmitted in both dominant and recessive forms. Its phenotypic covers a wide range of neurological and extraneurological symptoms. Nine genes that are all involved in nucleic acids (NAs) metabolism or signaling have so far been linked to the AGS phenotype. Recently, a link between autoimmune or neurodegenerative conditions and mitochondrial dysfunctions has been found. As part of the intricate system of epigenetic control, the mtDNA goes through various alterations. The displacement (D-loop) region represents one of the most methylated sites in the mtDNA. The term "mitoepigenetics" has been introduced as a result of increasing data suggesting that epigenetic processes may play a critical role in the control of mtDNA transcription and replication. Since we showed that RNASEH2B and RNASEH2A-mutated Lymphoblastoid Cell Lines (LCLs) derived from AGS patients had mitochondrial alterations, highlighting changes in the mtDNA content, the main objective of this study was to examine any potential methylation changes in the D-loop regulatory region of mitochondria and their relationship to the mtDNA copy number in peripheral blood cells of AGS patients with mutations in various AGS genes and healthy controls.Materials and methodsWe collected blood samples from 25 AGS patients and we performed RT-qPCR to assess the mtDNA copy number and pyrosequencing to measure DNA methylation levels in the D-loop region.ResultsComparing AGS patients to healthy controls, D-loop methylation levels and mtDNA copy number increased significantly. We also observed that in AGS patients, the mtDNA copy number increased with age at sampling, but not the D-loop methylation levels, and there was no relationship between sex and mtDNA copy number. In addition, the D-loop methylation levels and mtDNA copy number in the AGS group showed a non-statistically significant positive relation.ConclusionThese findings, which contradict the evidence for an inverse relationship between D-loop methylation levels and mtDNA copy number, show that AGS patients have higher D-loop methylation levels than healthy control subjects. Additional research is needed to identify the function of these features in the etiology and course of AGS.